The present invention relates to a method of isolating biologically active proteins which are acid-stable. The proteins are isolated from a biological extract of animal, vegetal or microbial origin.
The invention is in particular applicable for isolating on an industrial scale certain low molecular weight proteins the possible use of which in the pharmaceutical and food industry has been recently recognized.
Hitherto, the isolation of such proteins invariably required one or more chromatographic separation steps using, for example, ion exchange, gel permeation or affinity chromatography, which not only have the disadvantage of being very slow and very expensive but the application of which on a large scale is moreover limited for technical reasons.